If the Müllerian ducts fail to fuse, or, if the wall which is the result of fusion is not adequately resorbed, the result is a spectrum of uterine abnormalities called Müllerian fusion and absorption defects. The impact of these abnormalities on fertility is a subject for debate, but at least a subset seems to have a negative impact on reproductive performance manifesting in recurrent abortion and/or premature labor. Previous surgical interventions required laparotomy, but, with careful application of imaging techniques, a group of patients can be identified with a uterine septum amenable to removal under hysteroscopic direction with little morbidity. Intrauterine adhesions or synechiae are usually secondary to curettage in the context of missed abortion or pregnancy-related hemorrhage. These lesions cover a spectrum that ranges from minor and insignificant to severe cohesive adhesions that affect menstrual function and fertility. Surgical repair of the endometrial cavity affected with such adhesions presents a challenge to the hysteroscopic surgeon. Appropriate management is controversial but may include second loop hysteroscopy and the use of postoperative adjuvants such as systemic estrogens and intrauterine devices or systems designed to impede the development of adhesions.